CN109143374B - Method and system for imaging scattering body around well - Google Patents
Method and system for imaging scattering body around well Download PDFInfo
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- CN109143374B CN109143374B CN201810668383.8A CN201810668383A CN109143374B CN 109143374 B CN109143374 B CN 109143374B CN 201810668383 A CN201810668383 A CN 201810668383A CN 109143374 B CN109143374 B CN 109143374B
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/40—Seismology; Seismic or acoustic prospecting or detecting specially adapted for well-logging
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Abstract
The invention discloses a method and a system for imaging scatterers around a well, which are used for imaging tiny cracks around the well in exploration. The method provided by the invention comprises the following steps: acquiring orthogonal dipole four-component acoustic logging data; calculating a scattering decay quality factor Q according to the acoustic logging data, and compensating the acoustic logging data by using inverse Q filtering; acquiring transverse wave time differences in different directions, calculating the amplitude range of the direct wave by a least square method, and filtering the direct wave according to the amplitude range; suppressing the direct wave signals which are not filtered out by a median filtering method; then extracting scattered waves of the non-uniform bodies outside the well by an F-K filtering method; and imaging the scattered waves by using a Gaussian beam reverse time migration imaging method. By the invention, the existing exploration instrument can realize scatterer imaging, the problem of overhigh cost caused by special ultrasonic wave, radar and other technologies for imaging is avoided, and the operation is simplified.
Description
Technical Field
The invention relates to the field of exploration imaging, in particular to a method and a system for imaging a scatterer around a well.
Background
During exploration and development of calcium carbonate salt rock oil and gas reservoirs around deep or ultra-deep wells, reservoir formation, geological body morphology and orientation need to be measured. The azimuth imaging of the geologic body around the well is very important for optimizing the well position, acidizing and fracturing, and improving the oil and gas drilling rate and recovery ratio. In practice, the method has important reference significance for reducing underground scatterers and accurately drilling and exploiting by imaging small-scale slots and holes mainly comprising scattered waves.
At present, a four-component dipole transverse wave far detection slit-hole imaging technology is widely used, the slit-hole imaging can only be realized by a reflection linear inversion method aiming at a large-size slit hole, and when the slit hole is smaller than a small crack with the size of the acoustic wave wavelength 1/4, the imaging display is difficult. When the scatterers around the well are measured by the technologies such as ultrasonic waves, radars and the like, although small seam hole imaging can be realized, the method cannot be widely used in the drilling field due to the fact that the measurement cost is high, the operation is complex, and the method cannot cope with deep and severe measurement environments.
Therefore, it is necessary to provide a method that can realize small-seam-hole imaging, and is easy and convenient to operate and low in cost.
Disclosure of Invention
The embodiment of the invention provides a method and a system for imaging a scatterer around a well, which aim to solve the problems of complex operation and higher cost of the existing small-seam-hole imaging method.
In a first aspect, a method for imaging a scatterer around a well is provided, comprising:
s1, collecting orthogonal dipole four-component acoustic logging data with any determined depth and different orientations in a depth interval;
step S2, calculating scattering decay quality factors Q of different current depths and different azimuths according to the orthogonal dipole four-component acoustic logging data, and compensating the orthogonal dipole four-component acoustic logging data by using inverse Q filtering;
s3, acquiring transverse wave time differences of different directions at the current depth, calculating the amplitude range of the direct wave of each receiver shaft by a least square method, and filtering the direct wave in the orthogonal dipole four-component acoustic logging data according to the amplitude range;
step S4, pressing the direct wave signals which are not filtered out by a median filtering method;
s5, extracting scattered waves of the non-uniform bodies outside the well by an F-K filtering method according to the difference of the direct waves, the scattered waves and the reflected waves in the frequency-wave number domain;
step S6 is to image the scattered wave by a gaussian beam reverse time shift imaging method.
In a second aspect, there is provided a peri-wellbore scatterer imaging system comprising:
an acquisition module: the method is used for acquiring orthogonal dipole four-component acoustic logging data of any determined depth and different directions in a depth interval;
a compensation module: the system is used for calculating the scattering decay quality factor Q of the current depth in different directions according to the orthogonal dipole four-component acoustic logging data, and compensating the orthogonal dipole four-component acoustic logging data by using inverse Q filtering;
a filtering module: the method is used for obtaining the transverse wave time difference of different directions of the current depth, calculating the amplitude range of the direct wave of the shaft of each receiver through a least square method, and filtering the direct wave in the orthogonal dipole four-component acoustic logging data according to the amplitude range;
pressing the module: the device is used for suppressing the direct wave signals which are not filtered out by a median filtering method;
an extraction module: the method is used for extracting the scattered waves of the non-uniform bodies outside the well through an F-K filtering method according to the difference of the direct waves, the scattered waves and the reflected waves in a frequency-wave number domain;
an imaging module: and the method is used for imaging the scattered waves by a Gaussian beam reverse time migration imaging method.
According to the technical scheme, the embodiment of the invention has the following advantages:
in the embodiment of the invention, scattered waves are compensated through inverse Q filtering, direct waves in four-component sound wave data of the suppressed orthogonal dipole are filtered, and then scattered wave imaging is extracted, so that an exploration instrument can image the collected scattered waves, the problem of overhigh cost caused by the fact that the traditional measurement imaging needs to be carried out through special ultrasonic waves, radars and other technologies is solved, the problem that the existing logging instrument cannot process the scattered waves is solved, the imaging of scatterers is realized through existing exploration equipment on the basis of not additionally installing instruments, the operation is simplified, and the cost is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a flowchart of an embodiment of a method for imaging a scatterer around a well according to an embodiment of the present invention;
fig. 2 is a structural diagram of an embodiment of a borehole scatterer imaging system according to an embodiment of the present invention.
Detailed Description
The embodiment of the invention provides a method and a system for imaging scatterers around a well, which are used for imaging a seam hole around the well, reducing the cost of imaging the seam hole around the well and simplifying the operation.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an implementation process of the imaging method of the scatterer around the well according to the embodiment of the present invention includes:
s101, collecting orthogonal dipole four-component acoustic logging data of any determined depth and different directions in a depth interval;
the depth interval can be generally determined according to a target stratum, and acoustic data acquisition is carried out in the stratum interval of the target depth. The determined depth is a known formation depth, i.e., the position of the cross-dipole logging tool, which may be determined from the position of the drill bit, acoustic source, receiver, etc., and is not limited herein. The different orientations are generally at least required to ensure that 360 degrees of acoustic data can be acquired.
The orthogonal dipole four-component acoustic logging data generally includes all acoustic signals received by the receiver, which may include, but is not limited to, direct waves, scattered waves, and the like.
Optionally, the orthogonal dipole four-component acoustic logging data is converted into an earth coordinate system from a receiving instrument coordinate system.
Step S102, calculating scattering decay quality factors Q of different current depths and different orientations according to the orthogonal dipole four-component acoustic logging data, and compensating the orthogonal dipole four-component acoustic logging data by using inverse Q filtering;
the quality factor is used for representing the energy loss ratio, acoustic logging data are compensated through the quality factor Q, scattered waves with serious attenuation can be compensated, and extraction and imaging of the scattered wave data are facilitated.
Optionally, the step 102 specifically includes:
the method comprises the steps of (1) obtaining filtered dipole full-wave column data v (t) at a processing depth position, setting a window function g (t), and calculating power spectrums of actually measured waveforms at different moments by using short-time Fourier transform (STFT) (namely, the power spectrums are shown in a formula (1)).
Where t is time, ω is angular frequency, and f is frequency. The A (t, f) function gives the Fourier amplitude spectrum of the signal v (t) over a time window g (t) centered at t.
Step (2), constructing an objective function delta E which is a theoretical tail wave amplitude spectrum AC(t, f) and the measured tail wave amplitude spectrum A (t, f) as:
ΔE(t，f，QI，QS)＝|AC(t，f)-A(t，f)|2 (2)
wherein QIIs an intrinsic attenuation quality factor, QSIs the scattering attenuation quality factor. Theoretical amplitude spectrum A of the wake waveCAnd (t, f) can be calculated by a wake amplitude expression (namely, shown in the formula (3)) of the three-dimensional heterogeneous model.
Wherein, tdFor direct wave travel time, IDIs the amplitude A of the direct waveDIn the time window (t)1,t2) Is expressed as
Step (3) calculating a global minimum value Q of each receiver satisfying least square solving of the objective function delta EIAnd QSTaking the mean value of the scattering attenuation quality factors calculated by the N receivers of each depth point as the scattering of the depth pointAnd obtaining the scattering attenuation value of the depth point by taking the reciprocal of the emission attenuation quality factor as follows:
Atten＝1/QS
and (4) compensating the scattered wave signal received at the current depth according to the attenuation value.
S103, acquiring transverse wave time differences of different directions at the current depth, calculating the amplitude range of the direct wave of the shaft of each receiver by a least square method, and filtering the direct wave in the orthogonal dipole four-component acoustic logging data according to the amplitude range;
the direct waves are sound wave data which directly reach the receiver without reflection and refraction, the direct waves can interfere scattered wave imaging to a large extent, the signal-to-noise ratio of scattered signals can be improved by suppressing the direct waves, and then the imaging effect is improved.
S104, pressing an unfiltered direct wave signal by a median filtering method;
s105, extracting scattered waves of the non-uniform bodies outside the well by an F-K filtering method according to the difference of the direct waves, the scattered waves and the reflected waves in a frequency-wave number domain;
and step S106, imaging the scattered waves by a Gaussian beam reverse time migration imaging method.
Optionally, the step S106 specifically includes:
step S1061, solving the travel time and the path of the scattered wave according to a kinematics ray tracing equation;
step S1062, calculating Gaussian beam ray parameters according to a dynamic ray equation;
step S1063, calculating forward and backward continuation wave fields at each moment;
step S1064, calculating the forward and backward continuation wave fields by using deconvolution imaging conditions to obtain a Gaussian beam center imaging result;
and S1065, superposing all Gaussian beam center imaging results to obtain the scatterer imaging section.
Preferably, in the embodiment of the present invention, the well periphery may refer to a subsurface environment around an exploration well at a certain depth, the scatterers refer to subsurface holes which can make sound wave signals deviate from original paths and are scattered, and the holes are generally small in size.
In the embodiment of the invention, the scattered wave signal is finally obtained and imaged by processing the acoustic logging signal received by the existing exploration instrument, so that the problem that the small seam holes around the well cannot be imaged in the prior art is solved.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
Example two:
a method of imaging a peri-wellbore scatterer is described above generally, and a system for imaging a peri-wellbore scatterer is described in detail below.
FIG. 2 is a block diagram illustrating one embodiment of a system for imaging borehole-surrounding scatterers, in accordance with an embodiment of the present invention, the system comprising:
the acquisition module 21: the method is used for acquiring orthogonal dipole four-component acoustic logging data of any determined depth and different directions in a depth interval;
the compensation module 22: the system is used for calculating the scattering decay quality factor Q of the current depth in different directions according to the orthogonal dipole four-component acoustic logging data, and compensating the orthogonal dipole four-component acoustic logging data by using inverse Q filtering;
the filtering module 23: the method is used for obtaining the transverse wave time difference of different directions of the current depth, calculating the amplitude range of the direct wave of the shaft of each receiver through a least square method, and filtering the direct wave in the orthogonal dipole four-component acoustic logging data according to the amplitude range;
the pressing module 24: the device is used for suppressing the direct wave signals which are not filtered out by a median filtering method;
the extraction module 25: the method is used for extracting the scattered waves of the non-uniform bodies outside the well through an F-K filtering method according to the difference of the direct waves, the scattered waves and the reflected waves in a frequency-wave number domain;
the imaging module 26: and the method is used for imaging the scattered waves by a Gaussian beam reverse time migration imaging method.
According to the scatterer imaging system, signals such as the pressing direct wave and the like are filtered and suppressed after the original acoustic logging data are compensated, and then scattered wave imaging is extracted, so that on the basis of the existing equipment, scattered wave imaging is performed, not only can small slit hole imaging be realized, but also the imaging cost is reduced, and the operation is simplified.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art would appreciate that the modules, elements, and/or method steps of the various embodiments described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (4)
1. A method of imaging a borehole-surrounding scatterer, comprising:
s1, collecting orthogonal dipole four-component acoustic logging data with any determined depth and different orientations in a depth interval;
step S2, calculating scattering decay quality factors Q of different current depths and different azimuths according to the orthogonal dipole four-component acoustic logging data, and compensating the orthogonal dipole four-component acoustic logging data by using inverse Q filtering;
s3, acquiring transverse wave time differences of different directions at the current depth, calculating the amplitude range of the direct wave of each receiver shaft by a least square method, and filtering the direct wave in the orthogonal dipole four-component acoustic logging data according to the amplitude range;
step S4, pressing the direct wave signals which are not filtered out by a median filtering method;
s5, extracting scattered waves of the non-uniform bodies outside the well by an F-K filtering method according to the difference of the direct waves, the scattered waves and the reflected waves in the frequency-wave number domain;
step S6 is to image the scattered wave by a gaussian beam reverse time shift imaging method.
2. The method according to claim 1, wherein the step S1 further comprises:
and converting the orthogonal dipole four-component acoustic logging data into a terrestrial coordinate system from a receiving instrument coordinate system.
3. The method according to claim 1, wherein the step S6 includes:
step S61, calculating the travel time and the path of the scattered wave according to a kinematics ray tracing equation;
step S62, calculating Gaussian beam ray parameters according to a dynamic ray equation;
step S63, calculating the forward and backward continuation wave fields at each moment;
step S64, calculating the forward and backward continuation wave fields by using deconvolution imaging conditions to obtain a Gaussian beam center imaging result;
and step S65, superposing all Gaussian beam center imaging results to obtain the scatterer imaging section.
4. A system for imaging a borehole-surrounding scatterer, comprising:
an acquisition module: the method is used for acquiring orthogonal dipole four-component acoustic logging data of any determined depth and different directions in a depth interval;
a compensation module: the system is used for calculating the scattering decay quality factor Q of the current depth in different directions according to the orthogonal dipole four-component acoustic logging data, and compensating the orthogonal dipole four-component acoustic logging data by using inverse Q filtering;
a filtering module: the method is used for obtaining the transverse wave time difference of different directions of the current depth, calculating the amplitude range of the direct wave of the shaft of each receiver through a least square method, and filtering the direct wave in the orthogonal dipole four-component acoustic logging data according to the amplitude range;
pressing the module: the device is used for suppressing the direct wave signals which are not filtered out by a median filtering method;
an extraction module: the method is used for extracting the scattered waves of the non-uniform bodies outside the well through an F-K filtering method according to the difference of the direct waves, the scattered waves and the reflected waves in a frequency-wave number domain;
an imaging module: and the method is used for imaging the scattered waves by a Gaussian beam reverse time migration imaging method.
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| CN112114364B (en) * | 2019-06-21 | 2023-10-31 | 中国石油天然气股份有限公司 | Method and device for compensating dipole transverse wave reflected wave |
| CN111691876B (en) * | 2020-05-12 | 2023-05-09 | 中海油田服务股份有限公司 | Method, device and storage medium for imaging adjacent well by using acoustic logging |
| CN111580159B (en) * | 2020-05-12 | 2021-07-30 | 中国石油大学(北京) | Fracturing effect evaluation method and device based on microseismic quality factor |
| CN111736220B (en) * | 2020-05-13 | 2023-02-10 | 中国石油天然气集团有限公司 | Reverse time migration imaging method and device |
| CN112859163B (en) * | 2021-01-07 | 2022-08-30 | 中国石油大学(北京) | Method and device for determining stratum quality factor change of fracturing area by using scattered waves |
| CN113376629B (en) * | 2021-05-13 | 2022-08-05 | 电子科技大学 | In-well radar least square inversion method based on non-uniform input parameter grid |
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| CN104635268B (en) * | 2015-03-09 | 2017-03-08 | 成都晶石石油科技有限公司 | Quality factor computational methods under seismic data constraint |
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